Functional characterization of striated fiber assemblins in malaria parasites

项目摘要 疟疾是全世界疾病和死亡的一个重要原因，其中大多数死亡是由于 恶性疟原虫感染。人类疟疾的症状和体征是由无性生殖引起的。 寄生虫在人体红细胞中的复制。在这个临床上重要的血液阶段，恶性疟原虫 寄生虫通过无性生殖分裂-一个过程，其中产生几个子细胞的成分 在一个共同的细胞质内，然后分裂，一个同步的胞质分裂，产生单独的 侵略性的女儿被称为裂殖子的侵入性子寄生虫的产生发生在 高保真度，确保每个子细胞具有单个细胞核和所需的细胞器。分子 这种高度逼真的细胞核和细胞器分配的机制尚未完全理解， 疟原虫 对相关顶复门寄生虫弓形虫的研究鉴定了一个蛋白质家族，涉及 如条纹纤维蛋白（SFA），这是至关重要的寄生虫细胞分裂。SFAs被假设为 在分裂核的中心体和两者新形成的顶端之间形成连接 子体寄生在T.弓形虫内分泌SFA、PfSFA 1和PfSFA 2的恶性疟原虫直系同源物是 PfSFA2在全基因组转座子筛选中被发现。与此相反 数据，我们证明了这两个蛋白质是必需的无性复制在恶性疟原虫。基于 根据我们的初步数据，我们假设PfSFA1和PfSFA2在细胞凋亡过程中定位于一个类似于细胞凋亡的结构， 寄生体节在目前的建议中，我们将在一系列显微镜下测试这一假设。 测定。此外，我们还将通过表征寄生虫来评估PfSFA1和PfSFA2的功能 诱导性敲除后的停滞和形态学缺陷。为了更全面地了解 PfSFA1和PfSFA2的分子功能，我们将通过共- 免疫沉淀和通过邻近标记的间接或瞬时相互作用。通过确定一个鲁棒的 蛋白质相互作用网络的疟原虫SFAs，我们将建立基础，了解他们的 分子功能我们假设SFAs蛋白质是组织分割的关键 在恶性疟原虫的无性繁殖过程中。总之，拟议的研究将询问功能 这两个必需的蛋白质，并直接确定其在恶性疟原虫分割的作用。

PROJECT SUMMARY Malaria is an important cause of illness and death worldwide, with most of these deaths resulting from Plasmodium falciparum infection. The signs and symptoms of human malaria results from the asexual replication of parasites in human red blood cells. During this clinically important blood stage, P. falciparum parasites divide by schizogony – a process wherein components for several daughter cells are produced within a common cytoplasm and then segmentation, a synchronized cytokinesis, produces individual invasive daughters. The generation of the invasive daughter parasites, known as merozoites, occurs with high fidelity, ensuring that each daughter has a single nucleus and the required organelles. The molecular mechanism underlying this high fidelity of nuclear and organellar partitioning is incompletely understood in Plasmodium. Studies in the related Apicomplexan parasite Toxoplasma gondii identified a family of proteins, referred to as striated fiber assemblins (SFAs), that are critical for parasite cell division. The SFAs are hypothesized to form a connection between the centrosome of dividing nuclei and the newly forming apical ends of the two daughter parasites during T. gondii endodyogeny. The P. falciparum orthologs of the SFAs, PfSFA1 and PfSFA2, have been reported to be dispensable in a genome-wide transposon screen. In contrast to this data, we demonstrate that these two proteins are essential for asexual replication in P. falciparum. Based on our preliminary data, we hypothesize that PfSFA1 and PfSFA2 localize to a filament-like structure during parasite segmentation. In the current proposal, we will test this hypothesize in a series of microscopy assays. Furthermore, we will also evaluate the function of PfSFA1 and PfSFA2 by characterizing parasite arrest and morphologic defects following inducible knockout. To gain a more complete understanding of the molecular functions of PfSFA1 and PfSFA2, we will determine the direct protein interactions by co- immunoprecipitation and the indirect or transient interactions by proximity labeling. By determining a robust protein interaction network for the Plasmodium SFAs, we will establish the foundation to understand their molecular function. We hypothesize that the SFAs proteins are critical for organization of segmentation during the asexual replication of P. falciparum. Together, the proposed studies will interrogate the function of these two essential proteins and directly identify their role during P. falciparum segmentation.